In one aspect, this invention relates to a plug for tubulars. In another aspect, this invention relates to a pipe plug that is formed in the pipe. In yet another aspect, this invention relates to a pipe plug that is particularly useful for forming barriers downhole, such as downhole in oil and gas wells. In yet another aspect, this invention relates to a method for isolating pipe sections from each other. In a further aspect, this invention relates to a method for isolating a subterranean formation from a section of a pipe passing through the formation. In a further aspect, this invention relates to isolating one subterranean formation from another subterranean formation.
Pressure seals to isolate formations in a well are currently performed through the use of bridge mechanical plugs. It can be necessary to isolate formations, for example, where it is desired to flow fluid though one set of perforation in the well casing but not another set. This can be needed, for example, in fracturing operations. Isolation can also be needed, for example, in offshore situations where a zone is to be abandoned, and a re-completion to an upper zone (below the packer) is expected.
The bridge plugs currently used for such applications are mechanical devices that grab the casing walls by the use of slips, and isolate the pressure through the use of elastomers (that energize when the seals are deployed). For these types of bridge plugs to work under high differential pressures, the bridge plug body must have an outside diameter (OD) very close to the casing inside diameter (ID). Bridge plugs that are of small OD but expand to a large OD would be very valuable to the industry. This is because they could be run through the existing tubing and expanded to set in the casing. This operation could be accomplished without pulling the tubing, which is a very expensive operation. Unfortunately, these types of expandable mechanical bridge plugs cannot reliably withstand differential pressures of more than 3,500 psi (differential pressures), and differential pressures of between 3,500 and 15,000 psi are normally encountered.
A pressure seal that could be introduced through narrow passages and form a reliable seal would be very desirable.
A pressure seal that could reliably withstand a differential pressure of 3500 psi would be very desirable.
A pressure seal that has an OD which can conform to irregularities in its confining walls would be also very desirable.
Another problem encountered in the oil and gas industry is the pressurization of the annular space between two casing strings in a well. Where the pressurization reaches the surface, it must be removed. A technique to isolate the uphole portion of the annulus from fluid pressure in downhole portions of the annulus would be very desirable.
Other needs in the industry which can be met by the invention include:
An ability to pressure seal lateral junctions on horizontal wells;
The ability to plug open perforations that produce unwanted production in a well;
The ability to repair corroded, worn or damaged well casing;
The ability to control pressure in well control situations and blow-outs.
In one embodiment of the invention, there is provided a tubing containing a plug which was cast in the tubing.
In another embodiment of the invention, there is provided a method for isolating a first volume from a second volume by positioning a molten mass of material in a passage between the two volumes and permitting the mass to solidify and cool so as to form a highly pressure resistant seal across the passage.
Another embodiment of the invention provides a packer apparatus which is well suited to the practice of the above embodiments. The apparatus is provided in the form of a flexible container having a generally cylindrical sidewall and a bottom end closure. A mass of soldering composition is positioned in the container. An electrical resistance heating element is positioned adjacent to the mass of soldering composition. The electrical heating element can be activated to melt the soldering composition, and then deactivated to permit the soldering composition to solidify and seal. When removal of the packer is desired, the electrical heating element can be reactivated to remelt the solder and release the packer.